22 March 2005
BRITISH JOURNAL OF OPHTHALMOLOGY
New generation contact lenses cut risk of severe eye infection
[Incidence of keratitis of varying severity among contact lens wearers Br J Ophthalmol
2005; 89: 430-6]
Sleeping in contact lenses carries a significant risk of severe eye infection (keratitis), but the new
generation silicone hydrogel lenses cut that risk fivefold, finds research in the British Journal of
The findings are based on a year long study of patients attending the Royal Eye Hospital in
Manchester, UK, with acute eye problems.
All those wearing contact lenses were asked to supply details of lens hygiene, type, and pattern
of wear, including whether they slept in them.
Specialists scored eye problems on the cornea according to their severity, a score above 8
denoting severe keratitis. Eighty were scored below 8, defined as ‘non-severe keratitis,’ and 38
were scored above.
Among the 80 who scored below 8, 18 slept in their lenses. Among the 38 with severe keratitis, 9
Four types of lenses were studied - rigid, hydrogel daily disposable, hydrogel, and silicone
hydrogel. There were no differences in risk of severe keratitis between the different types of
lenses when they were worn during the day.
But the risk of severe keratitis rose when lenses were slept in, and there were some differences
between lens types.
Rates were 96 per 10,000 wearers a year for hydrogel lenses, compared with almost 20 per
10,000 wearers a year for silicone hydrogel lenses - a fivefold difference.
Almost 3 million people wear contact lenses in the UK, around 55,000 of whom live in the
catchment area served by the hospital, including 30,000 hydrogel lens wearers and 1700 silicone
hydrogel lens wearers.
But those wearing hydrogel lenses while they slept were five times more likely to develop severe
keratitis than those wearing silicone hydrogel lenses.
“Those who choose to sleep in lenses should be advised to wear silicone hydrogel lenses, which
carry a five times decreased risk of se